The long-term goal of the Vermont Diabetes Information System is to reduce morbidity and mortality from diabetes mellitus. The project will implement and evaluate a state-wide system to support evidence-based disease management by primary care providers, their practices and their patients in the community. The primary study question is: "What is the effect of a Diabetes Information System (including education, feedback and decision support) upon disease control measured by glycated hemoglobin?" Secondary questions address the effect of the system upon adherence to guideline recommendations, blood pressure control, patient satisfaction, medication use, functional status, and health care utilization. We hypothesize that the information system will result in improvements in the process and outcomes of clinical care. There are two specific aims: Aim 1: Implement the Diabetes Information System. Objective 1.1: Develop a registry of patients with diabetes in primary care practices in Vermont; Objective 1.2: Provide education and feedback to providers regarding their patients with diabetes; Objective 1.3: Deliver decision support (flow sheets, alerts and reminders), based on the registry and targeted at primary care providers and patients, to prompt ideal management of diabetes. Aim 2: Assess the Diabetes Information System. Objective 2.1: Assess disease control and guideline adherence by examining registry data in all subjects in a prospective, two-year, randomized controlled trial in 60 primary care practices; Objective 2.2: Assess outcomes (blood pressure control, obesity, functional status, symptoms, medication use, and satisfaction) by interview and examination in a sub-sample of patients from the controlled trial; Objective 2.3: Assess utilization of health care resources by analyzing administrative data in a sub-sample of patients from the controlled trial.